Details
| Original language | English |
|---|---|
| Pages (from-to) | 15-29 |
| Number of pages | 15 |
| Journal | Applied clay science |
| Volume | 16 |
| Issue number | 1-2 |
| Publication status | Published - Jan 2000 |
| Event | The 11th International Clay Conference (ICC'97) - Ottawa, Ont, Can Duration: 15 Jun 1997 → 21 Jun 1997 |
Abstract
MX-80 bentonites, which had been modified with hexadecylpyridinium (HDPy+), exhibit the capability of anion as well as cation adsorption and allow its use as effective sorbents for anionic as well as cationic pollutants in engineered barriers of waste repositories and in other geotechnical applications. Chemical and mineralogical properties of MX-80 bentonite undergo marked changes with increasing organophilicity. Mineralogical characteristics of the organo-bentonite samples were investigated by powder X-ray diffraction (XRD), by thermogravimetric (TG) and by calorimetric (DTA) measurements and by IR spectral analysis. Additionally, the exchange behaviour of HDPy+ and the dependence of surface charge on the degree of organophilicity were determined. The surface charge was measured by titration with charge compensating polyelectrolytes; the endpoint was at zero potential. On the basis of chemical and mineralogical analyses, it was concluded that the alkylammonium ions are adsorbed as (1) HDPy+ cations, (2) HDPyCl molecules and (3) micelles with decreasing binding intensities in this order. The observed uptake of the organic cations in excess of the cation exchange capacity (CEC) is due to hydrophobic interactions. HDPy+-uptake leads to the formation of a modified microstructure different from samples with relatively low HDPy+ saturation. As the organo-bentonites possess a fairly sufficient thermal stability up to 200°C, their use in engineered barriers for heat-generating pollutants such as nuclear waste, should be taken into consideration. (C) 2000 Elsevier Science B.V. All rights reserved.
Keywords
- Exchange behaviour, Mineralogical properties, Organo-bentonite, Surface charge, Thermal stability
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geology
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
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In: Applied clay science, Vol. 16, No. 1-2, 01.2000, p. 15-29.
Research output: Contribution to journal › Conference article › Research › peer review
}
TY - JOUR
T1 - Organophilic bentonites as adsorbents for radionuclides II. Chemical and mineralogical properties of HDPy-montmorillonite
AU - Dultz, S.
AU - Bors, J.
N1 - Funding information: The work is supported by the European Commission `Nuclear Fission Safety' programme (1994–1998) under contract FI4WCT950012.
PY - 2000/1
Y1 - 2000/1
N2 - MX-80 bentonites, which had been modified with hexadecylpyridinium (HDPy+), exhibit the capability of anion as well as cation adsorption and allow its use as effective sorbents for anionic as well as cationic pollutants in engineered barriers of waste repositories and in other geotechnical applications. Chemical and mineralogical properties of MX-80 bentonite undergo marked changes with increasing organophilicity. Mineralogical characteristics of the organo-bentonite samples were investigated by powder X-ray diffraction (XRD), by thermogravimetric (TG) and by calorimetric (DTA) measurements and by IR spectral analysis. Additionally, the exchange behaviour of HDPy+ and the dependence of surface charge on the degree of organophilicity were determined. The surface charge was measured by titration with charge compensating polyelectrolytes; the endpoint was at zero potential. On the basis of chemical and mineralogical analyses, it was concluded that the alkylammonium ions are adsorbed as (1) HDPy+ cations, (2) HDPyCl molecules and (3) micelles with decreasing binding intensities in this order. The observed uptake of the organic cations in excess of the cation exchange capacity (CEC) is due to hydrophobic interactions. HDPy+-uptake leads to the formation of a modified microstructure different from samples with relatively low HDPy+ saturation. As the organo-bentonites possess a fairly sufficient thermal stability up to 200°C, their use in engineered barriers for heat-generating pollutants such as nuclear waste, should be taken into consideration. (C) 2000 Elsevier Science B.V. All rights reserved.
AB - MX-80 bentonites, which had been modified with hexadecylpyridinium (HDPy+), exhibit the capability of anion as well as cation adsorption and allow its use as effective sorbents for anionic as well as cationic pollutants in engineered barriers of waste repositories and in other geotechnical applications. Chemical and mineralogical properties of MX-80 bentonite undergo marked changes with increasing organophilicity. Mineralogical characteristics of the organo-bentonite samples were investigated by powder X-ray diffraction (XRD), by thermogravimetric (TG) and by calorimetric (DTA) measurements and by IR spectral analysis. Additionally, the exchange behaviour of HDPy+ and the dependence of surface charge on the degree of organophilicity were determined. The surface charge was measured by titration with charge compensating polyelectrolytes; the endpoint was at zero potential. On the basis of chemical and mineralogical analyses, it was concluded that the alkylammonium ions are adsorbed as (1) HDPy+ cations, (2) HDPyCl molecules and (3) micelles with decreasing binding intensities in this order. The observed uptake of the organic cations in excess of the cation exchange capacity (CEC) is due to hydrophobic interactions. HDPy+-uptake leads to the formation of a modified microstructure different from samples with relatively low HDPy+ saturation. As the organo-bentonites possess a fairly sufficient thermal stability up to 200°C, their use in engineered barriers for heat-generating pollutants such as nuclear waste, should be taken into consideration. (C) 2000 Elsevier Science B.V. All rights reserved.
KW - Exchange behaviour
KW - Mineralogical properties
KW - Organo-bentonite
KW - Surface charge
KW - Thermal stability
UR - http://www.scopus.com/inward/record.url?scp=0034060079&partnerID=8YFLogxK
U2 - 10.1016/S0169-1317(99)00042-3
DO - 10.1016/S0169-1317(99)00042-3
M3 - Conference article
AN - SCOPUS:0034060079
VL - 16
SP - 15
EP - 29
JO - Applied clay science
JF - Applied clay science
SN - 0169-1317
IS - 1-2
T2 - The 11th International Clay Conference (ICC'97)
Y2 - 15 June 1997 through 21 June 1997
ER -